Command line arguments to make for working in Linux and Windows

Question

I have gone through the link Passing additional variables from command line to make.

I have a project which compiles both on Linux and Windows using makefiles. In Windows it uses gcc while in Linux it uses the ARM version of gcc ie armv7-linux-gcc. I would like to use a command line variable which tells the makefile which compiler to use depending on Windows or Linux.

For example in Windows it should have something like this:

CC= gcc  
CFLAGS= -c -D COMPILE_FOR_WINDOWS

and for Linux:

CC =  armv7-linux-gcc  
CFLAGS = -c -D COMPILE_FOR_LINUX

These preprocessor defines COMPILE_FOR_WINDOWS and COMPILE_FOR_LINUX are present in the code base and can't be changed.

Also for make clean it should clean up both for Windows and Linux. I can't assume that I people who build this will have Cygwin installed so can't use rm for deleting files.

Answer 1

This answer is only valid if you're using GNU make or similar:

Conditionally set your make variables using an Environment Variable.

For the 'clean' rule to function properly, you may also have to create a make variable for any differences in file extensions for either OS.

Naive example:

ifeq ($(OS), Windows_NT)
  CC=gcc
  RM=del
  EXE=.exe
  CFLAGS=-c -DCOMPILE_FOR_WINDOWS
else
  CC=armv7-linux-gcc
  RM=rm  
  EXE=
  CFLAGS=-c -DCOMPILE_FOR_LINUX
endif

PROG=thing$(EXE)

.PHONY: all
all: $(PROG)
        $(CC) $(CFLAGS) -o $(PROG) main.c

.PHONY: clean
clean:
        -$(RM) $(PROG) *.o